Honeycomb seal

ABSTRACT

A honeycomb seal which is manufactured by powder metallurgical injection molding is disclosed. The honeycomb seal is composed preferably of several segments. Each segment is embodied as a single piece and has a base element as well as honeycomb elements that are embodied as a single piece with the base element.

BACKGROUND AND SUMMARY OF THE INVENTION

This application claims the priority of International Application No.PCT/DE03/03856, filed Nov. 21, 2003, and German Patent Document No. 10259 963.7, filed Dec. 20, 2002, the disclosures of which are expresslyincorporated by reference herein.

The present invention relates to a honeycomb seal, which is preferablyused as a seal between a stationary component and a moving component, inparticular between a rotor and stator of a gas turbine.

Gas turbines, which are used as engines in airplanes for example, as arule include several stationary guide blades as well as several rotatingmoving blades. A stationary housing surrounds the guide blades and themoving blades. The rotating moving blades rotate relative to thestationary housing, wherein a radial gap is formed between the bladetips of the rotating moving blades and the housing. There is also acomparable gap between the radial inside ends of the guide blades andthe rotor bearing the moving blades. This radial gap should be kept assmall as possible in order to optimize the efficiency of the gasturbine. Hence it follows from this that even though the radial gap isrequired on the one hand to guarantee the rotatability of the movingblades vis-à-vis the housing, on the other hand, the radial gap isdisadvantageous for efficiency reasons.

As a result, honeycomb seals are used in gas turbines. The honeycombseals seal the radial gap between the rotating moving blades and thestationary housing, on the one hand, and, on the other hand, facilitatethe rotatability of the moving blades vis-à-vis the housing without theblade tips of the moving blades being damaged during rotation. Thesehoneycomb seals are used in the same way in the gap between the guideblades and the rotor. Moving blades can run directly against these typesof honeycomb seals with their blade tips or with the so-called sealingfins on their blade cover bands.

Prior art honeycomb seals are made of a basic body and honeycombelements, wherein the honeycomb elements and the basic body are separatecomponents, which are connected to each other via high-temperaturesoldering in a vacuum. The honeycomb elements are ground to size andthen deburred. The shape and size of the honeycomb elements is the samefor the most part. The design freedom of the honeycomb seal is limited.

Starting from this, the present invention is based on the objective ofcreating a novel honeycomb seal in which greater design freedom ispossible, and which is simpler to manufacture in terms of themanufacturing process.

According to the invention, the honeycomb seal is manufactured by powdermetallurgical injection molding. Powder metallurgical injection moldingis also designated as metal injection molding (MIM). The presentinvention proposes for the first time that a honeycomb seal bemanufactured by powder metallurgical injection molding. This results ingreater design freedom for the honeycomb seal. In addition, themanufacturing costs are lower. The grinding and deburring processingsteps are eliminated. In addition, a weight reduction is produced forthe honeycomb seal in accordance with the invention.

According to another aspect of the present invention, the honeycomb sealhas a base element and honeycomb elements that are embodied as a singlepiece with the base element. The honeycomb seal is preferably composedof several segments with honeycomb elements, wherein each segment has abase element and honeycomb elements that are embodied as a single piecewith the base element. As a result of this, it is possible to providethe honeycomb seal with different properties in sections, e.g., withdifferent geometries or material properties, in order to thereby adaptthe honeycomb seal in sections or in segments to the desired properties.

The honeycomb elements and the base element can be composed of differentmaterials, wherein the honeycomb elements, e.g., should be easy toabrade and the base elements should possess high temperature resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

Without being limited to these, exemplary embodiments of the inventionare explained on the basis of the drawings. The drawings show thefollowing:

FIG. 1 is a schematic, perspective side view of a honeycomb seal inaccordance with the invention as defined by a first exemplary embodimentof the invention.

FIG. 2 is a schematic, perspective side view of a honeycomb seal inaccordance with the invention as defined by a second exemplaryembodiment of the invention.

FIG. 3 is a schematic, perspective side view of a honeycomb seal inaccordance with the invention as defined by a third exemplary embodimentof the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 3 show different embodiments of honeycomb seals inaccordance with the invention. The honeycomb seals shown there arepreferably used to seal a gap between rotating moving blades and astationary housing of a gas turbine. Alternatively, the honeycomb sealsare used for sealing between guide blades and the rotor of a gasturbine. Thus, these types of honeycomb seals assume the task of sealinga radial gap between blade tips or sealing fins on cover bands of therotating moving blades and the stationary housing in gas turbines thatare used as aircraft engines for example. In order to achieve optimalefficiency of the gas turbine, the gap between the blade tips or sealingfins on the cover bands of the moving blades and the housing should beembodied to be as small as possible. However, so that the blade tips ofthe moving blades are not damaged during the rotation of the movingblades, the honeycomb seal must seal not only the radial gap, but alsoprotect the blade tips or sealing fins from damage.

FIG. 1 shows a honeycomb seal 10 in accordance with a first exemplaryembodiment of the invention. The honeycomb seal 10 shown is slid onto asupporting structure 11. The honeycomb seal 10 has a base element 12,wherein the base element 12 bears honeycomb elements 13. The baseelement 12 and the honeycomb elements 13 are embodied as a single piece.According to the invention, the honeycomb seal 10 is manufactured bypowder metallurgical injection molding. Powder metallurgical injectionmolding is also designated as metal injection molding. Details aboutthis manufacturing method are known from the relevant literature.

At this point it should be noted with respect to powder metallurgicalinjection molding that products manufactured with the aid of thismanufacturing process are distinguished by geometric design freedom. Inthe case of powder metallurgical injection molding, a metal powder ismixed with a binding agent to form a homogenous mass. The volume percentof the metal powder in this case is preferably greater than 50%.Injection molding is used to process this homogenous mass of bindingagent and metal powder. In this connection, molded bodies aremanufactured. In the case of the present invention, the molded bodiescorrespond to the honeycomb seal in accordance with the invention. Thesemolded bodies already feature all typical features of the desiredhoneycomb seal. However, they have a volume that is increased by thecontent of the binding agent. Subsequently, the molded parts aresubjected to a releasing process. Depending upon the binding agent used,it is either thermally disintegrated, vaporized or extracted via asolvent. The remaining porous molded bodies are then compressed viasintering using various inert gases or a vacuum to form the componentswith the final geometrical properties. The finished component isavailable once this is complete.

Consequently, it is within the meaning of the present invention tomanufacture the honeycomb seal 10, which is composed of a base element12 and of honeycomb elements 13 connected as a single piece with thebase element, using powder metallurgical injection molding.

The base element 12 of honeycomb seal 10 in FIG. 1 has lateral guidesections 14, which can be used to slide the honeycomb seal 10 on thesupporting structure 11. Consequently, the contour of the guide elements14 is adapted to the contour of the supporting structure 11 onto whichthe honeycomb seal 10 is supposed to be slid.

FIG. 2 shows a second honeycomb seal 15 in accordance with theinvention. The honeycomb seal 15 in FIG. 2 also has a base element 16and honeycomb elements 17 that are connected as a single piece with thebase element 16. Present again in the area of the base element 16 is aguide element 18, which can be used to slide the honeycomb seal 15 intoa supporting structure 19. The honeycomb seal 15 of the exemplaryembodiment in FIG. 2 is also manufactured using powder metallurgicalinjection molding.

Already at this point reference should be made to the fact that thehoneycomb seals 10 or 15 of the exemplary embodiments in FIGS. 1 and 2are preferably composed of several segments. Thus, several segmentswithin the meaning of the exemplary embodiments in FIGS. 1 and 2 can beslid onto the corresponding supporting structure. All segments then inturn have a base element 12 or 16 and honeycomb elements 13 or 17 thatare embodied as a single piece with the base element. As FIG. 3 shows,the segments have slots for circumferential sealing purposes and tongueson the opposing end of the segment. These tongues engage in the slots ofthe respective adjacent segments. The slots and the tongues aremanufactured as integral elements during the MIM process.

FIG. 3 shows another exemplary embodiment of a honeycomb seal 20 inaccordance with the invention. The honeycomb seal 20 shown there alsohas a base element 21 as well as honeycomb elements 22 embodied as asingle piece with the base element 21. FIG. 3 shows that the honeycombelements 22 have different geometric shapes, whereby different areas arepossible, in particular, in the axial direction.

The edges of the base element 21 serve as guide elements in order toslide the honeycomb seal 20 into a supporting structure 23. In theexemplary embodiment depicted in FIG. 3, the edge areas of the baseelement 21 accordingly form wedge-shaped guide elements 24, which engagein corresponding recesses in the supporting part 23 or are slid into thesupporting part.

The honeycomb seal 20 in the exemplary embodiment in FIG. 3 is alsopreferably composed of several segments. As FIG. 3 also shows, thesegment of the honeycomb seal 20 that is depicted in FIG. 3 has a recess25 on one end and a projection 26 on an opposing end. If severalsegments within the sense of FIG. 3 are positioned in the supportingstructure 23, then the segments interlock with each other to avoid axialrelative displacements. In this case, then a projection 26 of a segmentof the honeycomb seal 20 engages in a corresponding recess 25 of anadjacent segment. The segments of the honeycomb seal in the exemplaryembodiment in FIG. 3 are also manufactured using powder metallurgicalinjection molding.

The honeycomb seals 10, 15 and 20 of the exemplary embodiments accordingto FIGS. 1 through 3 possess a great degree of design freedom. Thus,honeycomb seals whose honeycomb elements can be individually adapted interms of their geometrical design can be manufactured with the aid ofpowder metallurgical injection molding. Using powder metallurgicalinjection molding to manufacture the honeycomb seal in accordance withthe invention reduces manufacturing expenditures. The grinding anddeburring of the honeycomb seal that are required by the prior art areeliminated. In addition, the honeycomb seals of the invention aredistinguished by a lower weight. This is particularly advantageous foraircraft engines. As a whole, the honeycomb seal in accordance with theinvention can be manufactured in a more favorable manner. Also possibleare higher manufacturing penetration and therefore value added.

Furthermore, it is possible for the honeycomb seals 10, 15, 20 to bemanufactured from another material than the supporting structures 11, 19or 23. Thus, the supporting structures can be manufactured from ceramicsfor example. In the case of the supporting structures 11, 19 or 23,these are components that are used in aircraft engines in the housing ofthe engines. The honeycomb seals 10, 15, 20 or segments of the honeycombseals can then be inserted in a simple manner into the supportingstructures 11, 19 or 23 that are fastened in the housing of the engine.

The honeycomb seals 10, 15 and 20 can also be manufactured as a singlepiece with the supporting structures 11, 19 or 23 using MIM technology,i.e., using powder metallurgical injection molding, wherein thisintegral part can be arranged directly in the housing.

Because of the low costs and the simple manufacturing, the honeycombseals 10, 15 and 20 can be used as disposable parts.

The precision of the MIM method to manufacture the honeycomb seal is sohigh that even the finest structures can be embodied, such as thehoneycomb elements 13, 17, 22, the tongue that cooperates with the slotor even part numbers.

1-14. (canceled)
 15. A honeycomb seal, in particular to seal a radialgap between a rotor and a stator of a gas turbine, wherein the honeycombseal is manufactured by powder metallurgical injection molding.
 16. Thehoneycomb seal according to claim 15, wherein the honeycomb seal iscomposed of several segments and wherein the segments are embodied as asingle piece and include a base element and honeycomb elements, andfurther wherein the base element bears the honeycomb elements.
 17. Thehoneycomb seal according to claim 16, wherein the segments aremanufactured by powder metallurgical injection molding.
 18. Thehoneycomb seal according to claim 16, wherein the segments areconnectable to a supporting structure and wherein the segments and thesupporting structure are manufactured of different materials.
 19. Thehoneycomb seal according to claim 18, wherein the base element of thesegments include at least one guide section, wherein the segments areconnectable to the supporting structure via the guide section, andwherein adjacent segments are interlocked with each other by aprojection of a first segment engaging with a corresponding recess of asecond segment.
 20. A honeycomb seal, in particular to seal a radial gapbetween a rotor and stator of a gas turbine, wherein the honeycomb sealhas a base element and honeycomb elements that are embodied as a singlepiece with the base element.
 21. The honeycomb seal according to claim20, wherein the honeycomb seal is composed of several segments, whereineach segment has a base element and honeycomb elements that are embodiedas a single piece with the base element.
 22. The honeycomb sealaccording to claim 21, wherein the base element of each segment includesat least one guide section and wherein each segment is connectable to asupporting structure via the guide section.
 23. The honeycomb sealaccording to claim 21, wherein a first end of the segments includes aprojection and a second end of the segments includes a recess andwherein the projection of a first segment is received within the recessof an adjacent segment.
 24. The honeycomb seal according to claim 22,wherein the segments of the honeycomb seal and the supporting structureare manufactured of different materials.
 25. The honeycomb sealaccording to claim 20, wherein the honeycomb seal is manufactured bypowder metallurgical injection molding.
 26. The honeycomb seal accordingto claim 22, wherein the honeycomb seal and the supporting structure aremanufactured as a single piece.
 27. The honeycomb seal according toclaim 18, wherein the honeycomb seal and the supporting structure aremanufactured as a single piece.
 28. The honeycomb seal according toclaim 15, wherein the radial gap sealed by the honeycomb seal liesbetween a rotating moving blade of the rotor and a housing of the statoror between a non-rotating guide blade of the stator and the rotor. 29.The honeycomb seal according to claim 20, wherein the radial gap sealedby the honeycomb seal lies between a rotating moving blade of the rotorand a housing of the stator or between a non-rotating guide blade of thestator and the rotor.
 30. The honeycomb seal according to claim 16,wherein the honeycomb elements and the base element are composed ofdifferent materials.
 31. The honeycomb seal according to claim 20,wherein the honeycomb elements and the base element are composed ofdifferent materials.
 32. A method for manufacturing a honeycomb seal forsealing a radial gap between a rotor and a stator of a gas turbine,comprising the step of manufacturing the honeycomb seal by powdermetallurgical injection molding.
 33. The method of claim 32, furthercomprising the steps of: subjecting a molded honeycomb seal to areleasing process to release a binding agent used in the powdermetallurgical injection molding process; and compressing the moldedhoneycomb seal after the releasing process via a sintering process. 34.The method of claim 32, further comprising the steps of forming thehoneycomb seal in a plurality of segments wherein each segment is formedas a single piece that includes a base element and honeycomb elementsand further wherein the base element bears the honeycomb elements. 35.The method of claim 34, further comprising the steps of connecting theplurality of segments to a supporting structure and manufacturing theplurality of segments and the supporting structure of differentmaterials.
 36. The method of claim 35, further comprising the steps ofconnecting a guide section of the base element to the supportingstructure and interlocking adjacent segments with each other by engaginga projection of a first segment with a recess of an adjacent secondsegment.
 37. A method of forming a honeycomb seal, in particular to seala radial gap between a rotor and stator of a gas turbine, comprising thestep of forming a base element of the honeycomb seal with honeycombelements of the seal as a single piece.
 38. The method of claim 37,further comprising the steps of: forming the base element in a firstmaterial; and forming the honeycomb elements in a second material. 39.The method of claim 37, further comprising the steps of: forming thehoneycomb seal in a plurality of segments, wherein each segment includesa base element and honeycomb elements; forming a first segment of theplurality of segments in a first material; and forming a second segmentof the plurality of segments in a second material.
 40. The method ofclaim 37, further comprising the steps of: forming the honeycomb seal ina plurality of segments, wherein each segment includes a base elementand honeycomb elements; forming a first segment of the plurality ofsegments in a first physical geometry; and forming a second segment ofthe plurality of segments in a second physical geometry.